From Medical Correspondent Dan Rutz

(CNN) -- Chemotherapy treatment for breast cancer patients several months before surgery may mean the difference between losing a breast to the disease or undergoing a less extensive operation, according to a new study.

The study, published in the August issue of the Journal of Clinical Oncology, finds chemotherapy several months before surgery shrinks breast tumors by more than half, in eight out of 10 patients.

"This study is a new approach to the treatment of early and middle-stage breast cancer," said Dr. Bernard Fisher of Allegheny University of Health Sciences.

The study indicates more women, including those with large tumors, might be able to safely undergo conservative surgery that cuts away a tumor rather than completely removing a breast.

Delaying the operation for chemotherapy treatment does not appear to increase the risk of cancer relapse.

"It can be used in any woman with the understanding and the total freedom that she's not being shortchanged by this kind of therapy," Fisher said.

A preferable alternative

Rita Carter was diagnosed with breast cancer two years ago and was offered chemotherapy before surgery. It shrunk her tumor enough that the surgeon was able to spare her breast.

"I know that mastectomies are not as extensive as they were in the past, but still, that just sounded good not to have to go through as much surgery," she said.

More women may be able to undergo preliminary chemotherapy to reduce extensive breast cancer surgery

Carter's surgeon, Dr. Toncred Styblo of Emory University in Atlanta, said the time may come when most chemotherapy will be given before, rather than after, breast cancer surgery.

"It downstages the cancer," he said. "So we find, statistically, that women who have preoperative chemotherapy have fewer lymph nodes involved with cancer than women who don't."

Fisher said there is another advantage to chemotherapy treatment. If the drugs work against large, measurable tumors, it is likely they'll take care of invisible, lingering cells that can sprout new tumors years later.

"Prior to this, one would have to wait until a woman had a failure in three years or five years," he said. "Then you say, the therapy she took didn't do so good."

Fisher said now that it's clear presurgical chemotherapy is safe, it will be possible to speed new drug testing.